Sliding door



April 21, 1964 1-. c. WHlTlNG SLIDING DOOR 2 Sheets-Sheet 1 Filed Nov.25, 1960 ATTORNEY 5.

April 21, 1964 T. c. WHlTlNG SLIDING DOOR INVENTOR H2O Mia??? 2Sheets-Sheet 2 Mi l ww ATTORNEYS.

United States Patent 3,12,752 SLIDING DOOR Theo C. Whiting, Ala-on, NYassignor to T. Whiting Mfg. Ina, Akron, N.Y., a corporation of New YorkFiled Nov. 25, 1950, er. No. 71,828 7 Claims. (Cl. 16t)363) Thisinvention relates to a door and is more particularly illustrated asembodied as a door for closed cargo trucks to close and renderweather-tight the doorway through which the cargo is taken into andremoved from the truck. However the invention can be embodied inclosures for stationary structures, such as garages, business places andhomes, or closures for other mobile structures.

One of the principal objects of the invention is to provide a closurewhich can be manually moved to its open and closed positions and whichis very low in cost while at the same time being of rugged constructionand standing up under conditions of severe and constant use Withoutgetting out of order or requiring repairs.

Another object is to provide such a door which is smooth and uniform inaction through the full range of opening and closing the same and whichis self-centering and occupies a minimum of cargo space.

Another object of the invention is to provide such a door which is freefrom rattles or other noises and which reliably seals the doorwayagainst the weather.

Another object of the invention is to provide such a doorway which canbe made of a wide range of materials in the form of laterally manuallyflexible sheets which are rigid in the direction of their broad surfacesso as to be capable of being pushed or drawn around or along curvedtracks. Suitable materials, in addition to sheet metal are opaque ortranslucent plastics.

Another object of the invention is to provide such a door which can bemade to have adequate rigidity and strength to resist heavy impacts,such being obtained either by the application of slats of wood or thelike to the laterally flexible sheets or by making these laterallyflexible sheets of corrugated form so as to be rigid against transversebending in one direction while at the same time being free to followcurved tracks in the other direction.

Another object is to provide such a door which is free from servicedifliculties and in which, in particular, the lubricant in the tracksproviding the sliding surfaces can be impregnated in liners for therails so as not to require replacement.

Another object is to provide such a door which can be readilycounterbalanced, especially when slats are pro vided, and in which thecounterbalancing mechanism is substantially wholly contained within therails along which the door moves so as to be out of sight and out ofdanger of being injured or accidentally injuring anyone.

Other objects and advantages of the invention will be apparent from thefollowing description and drawings in which:

FIG. 1 is a vertical longitudinal section through the rear end of atruck body having a rear door made in accordance with a simplified formof the present invention in which the door is not counterbalanced.

FIG. 2 is an enlarged fragmentary horizontal section through one of therear corners of the body across the doorway and the door therein, thissection being taken generally on line 2-2, FIG. 1.

FIG. 3 is a fragmentary enlarged view similar to FIG. 1 and showing ingreater detail a vertical transverse cross section through the upper endof the door when closed.

FIG. 4 is a fragmentary enlarged view similar to FIG. 1 and showing ingreater detail a vertical section through the sill of the doorway andthrough the bottom part of the door, this section being identified byline 44, FIG. 2.

3,129,752 Patented Apr. 21, 1964 FIG. 5 is a fragmentary verticallongitudinal section taken generally on line 55, FIG. 2 with the doorremoved and this section also being taken through the curved portion ofthe rail which joins its vertical part alongside the doorway to itsgenerally horizontal part extending under the roof.

FIG. 6 is a view similar to FIG. 2 and illustrating a modified form ofthe invention.

FIG. 7 is a fragmentary section taken generally on line 7-7, FIG. 6.

FIG. 8 is a fragmentary horizontal section taken generally on line 88,FIG. 6.

FIG. 9 is a fragmentary vertical section taken generally on line 99,FIG. 7.

FIG. 10 is a view similar to FIG. 4 of a further modifled form of theinvention.

FIG. 11 is a view similar to FIGS. 2 and 6 of the form of the inventionillustrated in FIG. 10.

FIG. 12 is a view similar to FIGS. 2, 6 and 11 of a still furthermodified form of the invention.

FIG. 13 is a view similar to FIGS. 5 and 7 of the modified form of theinvention illustrated in FIG. '12.

FIG. 14 is a view similar to FIGS. 2, 6, ll and 12 of a further modifiedform of the invention.

Referring more particularly to the form of the invention shown in FIGS.15, the numeral 10 represent-s the body of truck, this body having theusual floor or plat form 11, side walls 12. and roof 13, the rear end ofwhich roof is shown as extended downwardly, as indicated at 14, toprovide the upper limit of the doorway 16 at the rear of the truck bodyand which doorway extends from the floor to the bottom of the downwardextension 14 and from one side Wall 12 to the other. The bottom of thisdoorway is formed by a sill 18 which also forms the rear cross bar ofthe platform 11 and the upper part of this doorway is formed by ahorizontal transverse angle iron 19 which also forms one of thestructural members of the body. The cargo is loaded into the truck bodyand removed therefrom through this doorway.

In transit the doorway 16 is closed by a vertically movable door whichis made of one or more sheets 20, 21 of laterally manually flexiblesheet material which is rigid in the direction of its broad surfaces soas to be capable of being pushed or drawn along the straight and curvedportions of side tracks or rails indicated generally at 22. Each rail issuitably mounted at the sides '12 of the truck body to have a verticalstraight portion 23 along each side of the doorway 16, a curved portion24 continuing from the upper end of this straight portion 23 and curvingupwardly and horizontally toward the front of the truck body, and anupper straight portion 25 forming -a continuation of each curved portion24- and arranged in closely spaced relation to the roof '13 so as toprovide maximum cargo space within the body when the door is open.

Each of these tracks is preferably made of metal in the form of a tubeof C-shaped form in cross section to provide a longitudinal slot 26extending from one end of the rail to the other and being arranged alongthe center of each rail at that side 28 which opposes the other rail.The corresponding side edges of the sheets 20, 21. which comprise thedoor project through the slots 26 into the rails on opposite sides ofthe doorway, as best illustrated in FIG. 2.

To guide and permit sliding movement of the sheets 20, 21 along theseslots 26 of the two rails 22, the vertical part 23 of each rail is linedwith one or more lubricous graphite blocks 29 having a longitudinal slot30 in one side which is in register with and preferably considerablynarrower than the slot 26 in its rail, the width of the slot 30 beingpreferably sufficient to snugly receive the edges of the sheets 20, 21for free sliding movement therealong.

The slots 3%, 34 and 36 of the graphite blocks 29, 33'

and 35 form a continuous slideway for. the opposite edges of the sheetsZtl, 21 comprising the door so that the door can be manually slid alongthis way from the vertically closed position shown in-FIG. 1 to ahorizontal open position in which it is contained within the upperportion and curved portion 24 of the two rails 22 and contained withinthe slots 34 and 36 of the graphite blocks 33 and therein. If desiredthe series of blocks 35 can be held in position in the curved portion 24by projections 38 from the opposite ends of the curved rail portion 24into the endmost of the blocks 35; These projections can be produced inany suitable manner as by drilling a hole through the rail into each endblock 35 and then applying Weld metal to the hole to form the projectionwhich extends into the block 35. It will be seen that by thisarrangement the straight rail sections 23 and 2-5 can be separated fromthe connecting curved rail section 24 without having any of the graphiteblocks 35 fall out of the curved rail portions.

As previously indicated, the door is essentially composed of twoface-to-face sheets 24 21 of laterally manually flexible material whichare rigid in. the direction of their broad surfaces so as to be capableof being pushed or drawn around the curved ways providing by the slots36 contained within the graphite blocks 35 mounted in the curved portion24 of each side rail. These sheets can be sheet metal and by providingthem in the form of two sheets in face-to-face relation, they arerendered more readily flexible laterally than if they were a singlesheet of the same thickness while at the same time they jointly haveboth the thickness and planar rigidity to be readily pushed along therails and also to resist blows against their exterior surfaces such asare bound to happen in handling and transporting cargo. These two sheetscan also be made of other material having the necessary lateralflexibility and planar rigidity such as flexible sheet plastics.

It is desirable that the sheets have sliding contact with each other intheir direction of movement so as to provide a slight difierential inlength of the two sheets in rounding the curving portion 24 of eachtrack, the outer sheet 29 having a greater curvature than the innersheet 21 in this movement. For this purpose, while the sheets 26, 21 canbe of the same length in their direction of travel, one sheet ispreferably offset with reference to the other so that the outer sheethas, sa an offset 4% at its lower end and the inner sheet 21 has asimilar offset 40 at its upper end. Cross bars 42 preferably enclosethese opposite ends of the door and are each secured to thecorresponding oliset 4%) by a row of rivets 43. Desirably, these crossbars 42 are of double tubular form in cross section to provide an innertube 44 and an outer tube 45 separated by a longitudinal slot 46 whichreceives the ends of the door and through the walls of which slot thefastening rivets 46 extend. It will be noted that at each end of thedoor, the end of the non-riveted sheet stops short of the rivet asindicated at 48 in FIG. 3, this permitting the slight differentialsurface movement required when the two face-to-face sheets round thecurve 24. If desired, the sheets 28, 21 can be secured together midwaybetween their cross bars 42 as indicated by the rivets 49, FIG. 1, so asto positively hold these two sheets in the specific offset relationillustrated. A lubricant can be applied to the opposing surfaces of thetwo sheets.

While the lubricous graphite blocks 29, 33 and 35 provide adequate waysfor guiding the sheets 20, 21 to follow the changes in direction of theside rails 22, they are not adequate to hold these sheets in centeredrelation between these two rails. Thus, there would be nothing toprevent these sheets from, say; creeping to the right or left with theresult that their edges would cut deeper and deeper into the graphiteblocks at one side of the body and ultimately work themselves free fromthe opposite rail. To avoid this, a thrust bearing, indicated generallyat 5%, is provided at each end of each cross bar 42 to engage thosefaces 28 of the rails 22 which oppose each other, thereby to positivelyhold these bars, and hence the sheets 26, 21 connecting these bars, incentered relation with reference to the two rails. Such thrust bearingscan be of any form but each is shown as being in the form of a singlegraphite block 51 set into each end of each of the cross bars 42 for thedoor, as best illustrated in FIG. 2, and projecting from the cross bar asufiicient distance to snugly encounter the corresponding face 28 ofeach rail. These graphite blocks 51' can be held'in place in anysuitable manner as by inward projections 52 from the cross bar. As withthe projections 38, a simple way of providing the projections 52 is todrill holes through the ends of the cross bars 42 and into the graphiteblocks 51' and then apply abit of molten weld. metal to fill these holesand also weld to the metal of the cross bars- &2.

It will be seen that while the slots 3t), 34 and 36pmvide an adequateweather seal along the vertical sides of the closed door and while theengagement of its bottom cross bar of the door with the sill 13 providesan adequate weather seal at the bottom of the door, a substantialv spaceis left at the top of the door between it and the cross frame bar- H. Toprovide a weather seal across this space, a rubber strap 53 is securedto the underside of the cross frame bar 19 to extend the full width ofthe doorway and to have a flap or squeegeedike extension toward the doorand which engages the exterior face of the outer panel 20. This flap orextension sweeps along the door as'it opens or closes and provides aflexible seal against wind, rain, snow or dirt being driven into thebody through the space between the door and the upper cross bar 18 ofthe door opemng.

The door can be provided at its lower end with a handle 54 which isshown as being secured tothe outside of the door and hence is securedonly to-the outside sheet 20 of the door so as to avoid interferencewith the movement of'the inside sheet- 21 thereof.

In the operation of the form of 'the invention shown in FIGS. 15, toopen the door the operator seizes the handle 5'4 and lifts the same,this causing the opposite vertical edges of the two facc-to-faceflexible metal or plastic panels to move along the slots 3%? and'36 ofthe lubricous graphite blocks 29 and 35 of the vertical and curvedportions 23, 24 respectively of the two side rails 22. The advancingends of these Side edges of the two iace-to-face sheets 29, 21 areguided to enter the slots 34- of the graphite blocks 33 of thehorizontal section 25 of the two rails 22. When the handle reaches thetop of the door opening, the door is supported by the graphite blocks 33and 35 contained within the upper horizontal portions 25 and the curvedportions 24 of these rails.

During this movement, the flap or squeegee extension 53 of the rubberstrap across the top cross bar 1Q of the door frame sweeps against theoutside face of the door so as to provide a continuous weather seal.Also, during this movement, the door is held in centered relationbetween the two rails 22 by the graphite thrust bearing blocks 51secured to project from each end of each cross bar ll; of the door intoengagement with the opposing faces 28 of the side rails 22. By makingthe door of two sheets of flexible material instead of one, greaterlateral flexibility is provided in rounding the curved portions 24 ofthe rails than if a single sheet having the same thickness as the twosheets were. provided while at the same time the door is madesufficiently thick so as to be 3,1 completely rigid in the direction ofits broad faces and also sufliciently thick to withstand accidentalblows against its sides such as are incident to doors for cargocarriers.

In the form of the invention illustrated in FIGS. 68, the truck body isthe same as illustrated in FIGS. 1-5, and hence the same referencenumerals have been employed. The form of the invention shown in FIGS. 68is designed for a much heavier and sturdier door, the door being bothcounter-balanced and also being provided with wooden slats to withstandblows from cargo handling against the door which otherwise might dent orbend the simple two-ply door construction shown in FIGS. 1-5.

As with the form of the invention shown in FIGS. 15, the body of thedoor comprises two sheets 60 and 61 arranged in face-to-face relationwith each other and made of flexible metal or plastic so that they canmanually be moved to track around a curve, but at the same time arerigid in the direction of their broad faces so that they can neither bepushed or pulled around such curves. Also as with the form of theinvention shown in FIGS. 15, the opposite vertical edges of this doorare constrained to move along rails 62 at opposite sides of the door andbody, each of these rails having a bottom vertical part 63 secured alongthe vertical sides of the doorway 16 and leading to an upper curved part64 which curves toward the front of the truck body and which leads to ahorizontal top part 65, arranged in closely spaced relation below theroof 13 of the body. As with the form of the invention shown in FIGS.l-5 each of these rails 62 is of C-shaped tubular form in cross section,having a longitudinal slot 66 in that wall or face 68 which opposes theopposite rail.

The vertical edges of the flexible sheets 60, 61 project through theseslots 66 into the interiors of the two rails 62 and are shown as guidedbetween a pair of lubricous strips 69 set into suitable grooves 76 atopposite sides of the slot 66 to have portions projecting into this slotto engage the opposite sides of the door as hereinafter set forth. Thesestrips or pieces 69 can be made of any lubricous material to have therequired firmness, strength and lubricity to guide the door along thecurved and straight portions of the side rails with minimum manualeffort. For example, the strips can be made of wood fiber with, say 20%impregnated graphite. These strips could have about the same hardness asconventional hardboard panels, with graphite added. Alternately thesestrips could, of course, be made of various other materials.

To provide increased protection to the door from shifting cargo within,the door is shown as being provided with horizontal wooden slats 71covering its inside face. These slats are shown as having longitudinalgrooves 72 provided in their opposing longitudinal edges, and each pairof grooves slidingly receives a strip of metal 73 having bent ends 74engaging the ends of the slats to prevent longitudinal displacement ofthese strips. It will be apparent that these strips maintain substantialalinement of the slats while permitting edge separation thereof whenpassing around the curved portion of the rail, as well as permitting theslats to come into closely spaced edge to edge relation on traversingthe vertical and horizontal portions of the rails. In addition, topermit of free travel around the curved sections 64 of the two rails,the faces 75 of these slats which oppose the sheets 66, 61 arepreferably rounded to conform to this curvature as best illustrated inFIG. 7.

Each slat is preferably secured at its center by a line of rivets 76 tothe inside sheet 61 thereby to leave the outside sheet 69 free to movealong the inside sheet in conforming to the differential in curvaturebetween these two sheets when rounding the curved portions 64 of therails. For strength the slats 71 preferably extend the full width of thesheets 64), 61 and are interposed between and have sliding contact withone of the lubricous strips 69. Instead of the upper and lower crossbars used with the form of the invention shown in FIGS. 15, the upperand lower edges of the sheets 60, 61 of the door are shown as bentaround the end edge of the end slats, as indicated at 78, thereby toprovide a rounding nose at both the top and bottom of the door and whichnose is sufiiciently flexible to permit the slight expansion of thesheets relative to each other due to the differential in curvature inrounding the curved portions 64 of the rails.

Instead of graphite blocks to provide thrust bearings at each of thefour corners of the door, these thrust bearings are each in the form ofa ball 79 provided at each of the four corners of the door to engage theface 68 of the corresponding rail and hold the door in centered relation to these rails as it is moved from open to closed position and viceversa. These balls are shown as held within a body 86 in which theseballs are freely revolvable and each of these bodies is shown as securedwithin a socket 81. Each socket is shown as having a flange 82 by meansof which the socket can be screwed, as indicated at 83, to each end ofthese top and bottom end slats 71 for the door.

A particular feature of the form of the invention shown in FIGS. 69, isthat the door is counterbalanced. For this purpose a pair of longhelical tension springs 85, 85a are arranged side by side within each ofthe tubular rails 62 along the inside of the inner sheet 61 of the dooras best shown in FIG. 6. One end each spring 85, 85a is fixed to abracket 86 which is in turn secured to the lowerrnost corner of the dooragainst corresponding bottom slat 71 as by a rivet 88 as shown in FIGS.6 and 8. The opposite end of each spring 85, 85a is shown as secured toan eye 89, or other suitable fastening, to an end head 90 at the freeend extremity of the horizontal upper section 65 of the correspondingrail 62. At the curved portion 64 of each rail each pair of springspasses around a series of pairs of rollers 91 each pair being journalledon a pin 92 suitably secured to the corresponding side wall 12 of thebody as best shown in FIG. 9. The inner or shorter curving side of eachcurved track section 64 is provided with a slot 93 through which theserollers project to support the corresponding portion of the pairs ofsprings 85, 85a in general conformity with the curved section 64 of thetrack as best illustrated in FIG. 7.

In the use of the form of the invention shown in FIGS. 6-9, the door ismanually raised and lowered and in doing so the flexible sheets 60 and61 and wooden cross slats 71 move between and in contact with thelubricous strips 69 which are preferably impregnated with a lubricant toinsure easy movement of these parts along these strips. These strips arearranged longitudinally in the side rails 62 on opposite sides of theslot 66 through which the sides of the door project into these slots andto hold the door in centered relation while moving along these rails,the thrust bearings, each in the form of the ball 79, are provided ateach of the four corners of the door to engage the 0pposing faces 68 ofthe rails and thereby prevent displacement of the door to the right orleft with reference to its rails.

The wooden slats 71 add considerably to the weight of the door inproviding protection against heavy blows and to compensate for thisweight the pairs of counterbalance springs 85, 85a are provided. As thedoor lowers, these pairs of springs are stretched out, theirintermediate portions travelling over the arcuately arranged pairs ofrollers 91 so that the strain upon the springs is distributed along allof the coils thereof and not concentrated at the ends of the springsattached to the door. It will also be particularly noted that the pairsof springs are completely housed, and that the counterbalancingmechanism is essentially contained within the same rails which supportand guide the door in its opening and closing movement.

The use of the helical springs 85, 85a in pairs and in side-by-siderelation is an important feature of the invention. Thus a single spring35 at each side of the door could not be made to stand up, the springsbreaking down under service conditions. The use of a pair of springs 85,85a at each side of the door travelling around the pairs of rollers d6as shown provides a complete solution to this fundamental defect.Apparently the problem had to do with the much larger diameter springrequired when the use of only one spring at each side of the door wasattempted. Thus while the combined torsional forces from both stretchingthe spring and bending the spring around a curve resulted in rapidbreakdown of the larger diameter single springs, this result was whollyeliminated when the pair of smaller diameter springs 85, as shown, weresubstituted.

With the smaller diameter springs so arranged side-byside in pairs ateach side of the door, danger is present, however, of having the coilsof the springs intermesh with each other and, on contracting, causingfailure of the springs to operate. To avoid this, as best illustrated inFIG. 8, the coils of one spring 85 are arranged so as to he pitched inone direction, say clockwise, while the coils of the companion spring85a are arranged to be pitched in the opopsite direction, saycounter-clockwise. In this manner, with the degree of separation of thecoils which obtains under actual service conditions, the coils of onespring cannot intermesh with the coils of the other and hence the dangerof the springs becoming tangled together and becoming inoperative iseliminated.

In the form of the invention shown in FIGS. and 11 the truck body is thesame as illustrated in the preceding figures and the same referencenumerals have therefore been employed. The form of the invention shownin FIGS. 10 and 11 illustrates a modification of the invention in whichthe manually laterally flexible sheet, which is the principal componentof the door, is in the form of a horizontally corrugated sheet. Thepurpose of such corrugations is, of course, to give transverse strengthto the door Without the use of wooden slats as with the form of theinvention as shown in FIGS. 69, and at the same time without interferingwith the easy flexing of the door while travelling around the arcuate orcurved portion of its rails.

For this purpose, the door is shown as including two manually flexiblecorrugated sheet metal or plastic sheets 1430 and 151, these sheetsbeing arranged in interfitting, face-to-face relation with theircorrugations mating and extending horizontally. As with the other formsof the invention, each rail 102 is of tubular form and of C- shaped formin cross section to provide a slot 103 in its side face 104, theseslotted side faces 104- of the two rails opposing each other andreceiving the opposite ends of the corrugated sheets 1%, 101. To guidethe corrugated sheets, each rail can be lined with blocks 105 ofgraphite, similar to graphite blocks in the form of the invention shownin FIGS. l5. Also, to hold the doorway centered thrust bearings 106 areprovided at each of its four corners to engage the face 104. The thrustbearings 106 can each take the form shown in FIGS. 69, namely a ball 10Srevolvably contained within a bracket 109 secured to the inner sheet101. The sheets 100, 101 can be joined at their opposite ends by a bead110, this being shown as formed by bending one of the sheets around theother as shown in FIG. 10.

With the form of the invention shown in FIGS. 12 and 13, the truck bodyis the same as shown in conjunction with the other forms of theinvention and the same reference numerals have been applied. The form ofthe invention shown in FIGS. 12 and 13 is particularly characterized bythe use of wooden slats on the exterior of the door as compared with theinterior wooden slats shown in the form of the invention illustrated inFIGS. 69.

The main body of the door is shown as being in the form of a singleflexible sheet 115 of metal or plastic to the exterior of which aplurality of horizontal wooden slats 116, quite similar to slats 71 ofFIGS. 69, are

secured in closely spaced vertical relation as by rivets 1-18 passingthrough the center of each slat and anchoring in the sheet 115. As withthe other forms of the invention, this door is slid along side railsindicated generally at 119 of tubular form and C-shaped in cross sectionto provide longitudinal slots 129 in that side 121 of each rail whichopposes the opposite rail. The opposite edges of the door project intothese slots of the two rails and are contained within and slide along aslot 122 in a block 123 of graphite or lubricant impregnated material.The blocks 123 can be of the same form as the graphite blocks used inthe form of the invention illustrated in FIGS. 1-5. One side of thegraphite blocks 123 engages the inner face of the flexible sheet and theother side of these graphite blocks engages the outer faces 125 of thewooden slats 116 at the opposite extremities thereof. T 0 this end theouter faces 125 of these wooden slats, at least at their extremitieswhich engage the graphite blocks 123, are curved so as to have fullsurface contact with the graphite blocks 123, when travelling around thecurved part of the rail as illustrated in FIG. 12. To maintain the doorin centered relation between the rails 119, every tenth or so 512111 116is made longer than the others to project further at its opposite endsand have sliding contact with the bottoms of the grooves 122.

When used on the exterior, it is also desirable to provide a weatherseal between the several slats. Such a weather seal can be of any formbut is shown as being in the form of a strip of metal 126 like Strips 73of FIGS. 69, slidingly fitted in longitudinal grooves 128 provided inthe opposing edges of the succession of wooden slats 116 and having bentends 129 engaging the ends of the slats to prevent longitudinaldisplacement of these sealing strips. It will be seen that these strips,like strips 73 of FiGS. 69, prevent cocking of the slats, whilepermitting edge separation of the wooden slats 116 when passing aroundthe curved portion of the rail as well as permitting these slats to comeinto closely spaced edge-to-edge relation on traversing the vertical andhorizontal portions of the rail.

In the form of the invention illustrated in FIG. 14, the body is thesame as with the other forms of the invention and the same referencenumerals have been applied. As with the form of the invention shown inFIGS. 1-5, the door illustrated in FIG. 14 is composed of two sheets139, 131 of flexible metal or plastic arranged in face-toface relationwith. each other so as to be manually flexible laterally but to bestable or rigid in the direction of their broad faces. As with the otherforms of the invention illustrated, the opposite edges of the sheets130, 131 are guided in a rail 132 secured to the truck body and alongwhich the sheets slide. The rail 132 is of C-shaped form in crosssection to provide a longitudinal slot 133, the slots of the two railsopposing each other and the opposite edges of the sheets 13 1 beingcontained within these slots. Each rail 132 is shown as being in theform of a thick walled metal extrusion as compared with the other formsof the invention illustrated wherein sheet metal is used, and thisextrusion is shown as having an enlarged through bore 134 extendingalong inner end of the slot 133. This bore and the slot 133 are linedwith a sheet 135 of material having a high degree of lubricity, such asnylon, which is inherently lubricous although any other lubricous linercould be used.

In the slot 133 this liner slidingly engages the outer sides of thesheets 13%, 131 and provides a way along which these sheets are guided.This liner tightly embraces a large wire 136 which serves to anchor thesame in posi tion. The rail can readily be produced by spreading thejaws of the rail, inserting the liner .135 and wire 136, and thenbringing the jaws together to clamp the wire 136 and thereby securelyhold the liner 135 in operative position.

In other respects, the form of the invention illustrated in FIG. 14 canfollow that form of the invention illustrated in FIGS. 1-5.

From the foregoing, it will be seen that the present invention providesa very simple door particularly a sliding door in which the principalelements are one or more sheets which are laterally manually flexiblebut rigid in the direction of their broad surfaces so as to be capableof being pushed or drawn along or around curved rails. It will also beseen that the door can be centered by the pro-vision of simple thrustbearings at each of its corners and which travel along and engage theopposing sides of the rails in which the edges of the door arecontained. It will also be noted that a simple guide and support forthese sheets are provided by a pair of side rails which are C-shaped incross section to provide opposing slots containing the opposite verticaledges of the sheets and by the use of suitable lubricous blocks orstrips within the rails to engage and slidingly support the sheets. Itwill also be noted that the door can be given the required resistance toimpacts either by the addition of wooden slats or by corrugating thesame, and that it can be rendered counterbalanced by a simple extensiblespring housed within the tubular rails, this latter feature also beingapplicable to doors of a construction other than illustrated.

What is claimed is:

l. A door for the doorway in a structure, comprising a pair of parallelmetal rails arranged along opposite sides of said doorway and havingparallel portions curving away from said doorway, said rails being ofchannel form in cross-section to provide channels extendingsubstantially the full length thereof with the open mouths of saidchannels being in opposed relation to each other, a laterally manuallyflexible sheet which is rigid in the planar direction of its broad facesand has opposite generally parallel edge portions contained in saidchannels, bearings fixed to each rail along each side of its mouth andextending substantially the full length of its rail and slidinglysupporting and guiding said end portions of said sheet to travellengthwise of said rails, horizontal bars fixed to opposite ends of saidsheet along the leading and trailing edges thereof, and thrust bearingssecured to opposite ends of said horizontal bars and engaging opposingexternal sides of said rails to maintain said sheet in centered relationto said rails.

2. A door for the doorway in a structure, comprising a pair of parallelmetal rails arranged along opposite sides of said doorway and havingparallel portions curving away from said doorway, said rails being ofC-shaped form in cross-section to provide opposing parallel months intheir opposing size and extending substantially the full length thereof,a laterally manually flexible sheet which is rigid in the planardirection of its broad faces and has opposite generally parallel edgeportions contained in said mouths, a lubricous body fixed to each railon each side of its mouth and extending substantially the full length ofits rail and slidingly supporting and guiding said edge portions of saidsheet to travel lengthwise of said rails, means maintaining said sheetin centered relation to said rails, a vertical series of horizontalslats each of rounding convex form in cross section on its side facingsaid sheet, and means securing said slats. along their horizontalcenterlines to said sheet the opposite ends of said slats being arrangedbetween and slidingly engaging said lubricous bodies.

3. A door for the doorway in a structure, comprising a pair of parallelmetal rails arranged along opposite sides of said doorway and havingparallel portions curving away from said doorway, said rails being ofC-shaped form in cross-section to provide opposing parallel mouths intheir opposing size and extending substantially the full length thereof,a laterally manually flexible sheet which is rigid in the planardirection of its broad faces and has opposite generally parallel edgeportions contained in said mouths, a lubricous body fixed to each railon each side of its mouth and extending substantially the full length ofits rail and slidingly supporting and guiding said edge portions of saidsheet to travel lengthwise of said rails, means maintaining said sheetin centered relation to said rails, a vertical series of horizontalslats secured along their horizontal centerlines to said sheet and saidslats being provided along their opposing edges with mating grooves, andstrips of metal contained within each pair of said mating grooves tobridge the spaces between said slats.

4. A door for the doorway of a structure, comprising a pair of parallelvertical metal rails arranged along opposite sides of said doorway andhaving upper parallel portions curving in a horizontal direction awayfrom said doorway and continued in generally horizontal extensions, saidrails being of channel-shaped form in cross section to provide channelsextending substantially the full length thereof with the open mouths ofsaid channels being in opposed relation to each other, a laterallymanually flexible sheet which is rigid in the planar direction of itsbroad faces and has opposite generally parallel edge portions containedin said mouths of said channels, bearing means extending along each sideof each of said mouths substantially the full length of said rails andslidingly supporting and guiding said edge portions of said sheet totravel lengthwise of said rails, and a helical tension spring containedin the inner part of each of said channels and extending substantiallythe full length of said channels in the closed position of the sheet,means connecting one end of each spring to the end of the correspondingextension remote from the corresponding curving portion and meansconnecting the opposite end of each spring within said channel to thecorresponding bottom corner of said sheet.

5. A door as set forth in claim 4, wherein each spring is supported byand travels around an arcuately disposed set of rollers having axesparallel with the axis of said curving portions and each projectingthrough an arcuate slot in the smaller arcuate wall of each of saidcurving portions.

6. A door as set forth in claim 4 wherein said helical compressionsprings comprise a pair of helical compression springs arranged side byside in the inner part of each of said channels.

7. A door as set forth in claim 6 wherein the coils of the springs ofeach pair are pitched to spiral in opposite directions to preventintermesbing of the convolutions thereof as the springs of each pair arestretched and released.

References Cited in the file of this patent UNITED STATES PATENTS1,868,233 Hungerford July 19, 1932 2,258,971 Carlson Oct. 14, 19412,258,972 Carlson Oct. 14, 1941 2,288,711 Hufferd et al July 7, 19422,827,115 Stroup Mar. 18, 1958 2,827,118 Wendt Mar. 18, 1958 2,835,539Conrad May 20, 1958 2,886,481 Swan May 12, 1959 2,892,663 Nickerson June30, 1959 2,914,775 Kaufr'man Dec. 1, 1959 2.938.578 Stull Mat! 31-. 1 60

1. A DOOR FOR THE DOORWAY IN A STRUCTURE, COMPRISING A PAIR OF PARALLELMETAL RAILS ARRANGED ALONG OPPOSITE SIDES OF SAID DOORWAY AND HAVINGPARALLEL PORTIONS CURVING AWAY FROM SAID DOORWAY, SAID RAILS BEING OFCHANNEL FORM IN CROSS-SECTION TO PROVIDE CHANNELS EXTENDINGSUBSTANTIALLY THE FULL LENGTH THEREOF WITH THE OPEN MOUTHS OF SAIDCHANNELS BEING IN OPPOSED RELATION TO EACH OTHER, A LATERALLY MANUALLYFLEXIBLE SHEET WHICH IS RIGID IN THE PLANAR DIRECTION OF ITS BROAD FACESAND HAS OPPOSITE GENERALLY PARALLEL EDGE PORTIONS CONTAINED IN SAIDCHANNELS, BEARINGS FIXED TO EACH RAIL ALONG EACH SIDE OF ITS MOUTH ANDEXTENDING SUBSTANTIALLY THE FULL LENGTH OF ITS RAIL AND SLIDINGLYSUPPORTING AND GUIDING SAID END PORTIONS OF SAID SHEET TO TRAVELLENGTHWISE OF SAID RAILS, HORIZONTAL BARS FIXED TO OPPOSITE ENDS OF SAIDSHEET ALONG THE LEADING AND TRAILING EDGES THEREOF, AND THRUST BEARINGSSECURED TO OPPOSITE ENDS OF SAID HORIZONTAL BARS AND ENGAGING OPPOSINGEXTERNAL SIDES OF SAID RAILS TO MAINTAIN SAID SHEET IN CENTERED RELATIONTO SAID RAILS.